Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint=false and destructiveHint=false, so the description doesn't need to restate safety. The description adds the behavioral context that the attachment enables retrieval, which is useful. However, it doesn't disclose whether attaching replaces an existing store, whether it's idempotent, or whether it requires the agent to be in a certain state.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is a single sentence that front-loads the action and purpose. It is concise and free of fluff, though it could add a brief note about alternatives without becoming verbose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a simple two-parameter attach operation with full schema coverage, the description is adequate. However, it doesn't mention the effect of attaching (e.g., whether it replaces existing attachments) or any prerequisites, and there is no output schema to clarify the return value. The sibling list shows many attach_* variants, so a brief differentiator would improve completeness.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents both parameters. The description adds no additional meaning beyond what the schema provides, so the baseline 3 applies.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb ('attach') and resource ('vector store (knowledge base)') and clarifies the purpose ('so the agent can retrieve from it'). It distinguishes from siblings like detach_vector_store and create_vector_store, though it doesn't explicitly name them.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies the tool is used to give an agent retrieval access to a knowledge base, and the sibling list shows related attach_* tools. However, it doesn't explicitly state when to use this over attach_file or attach_mcp_server, nor does it mention prerequisites like the store needing to exist or be created first.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.